U.S. patent number 6,741,779 [Application Number 10/389,398] was granted by the patent office on 2004-05-25 for high contrast front projection display panel and a method of making a high contrast front projection display panel.
This patent grant is currently assigned to Scram Technologies, Inc.. Invention is credited to James T. Veligdan.
United States Patent |
6,741,779 |
Veligdan |
May 25, 2004 |
High contrast front projection display panel and a method of making
a high contrast front projection display panel
Abstract
An optical display panel which provides improved viewing
contrast for front projection applications, and a method of
producing a stacked optical waveguide panel for front projection
applications, are disclosed. The optical panel includes a plurality
of stacked optical waveguides, wherein each waveguide has a back
face and an outlet face at opposing ends of each waveguide, and
wherein each waveguide is formed of a core between an opposing pair
of cladding layers, and at least one reflector connected to the
back face of at least one waveguide, wherein the at least one
reflector receives image light incident through at least one
waveguide from the outlet face, and wherein the at least one
reflector redirects the image light back through the at least one
waveguide out of the outlet face. In the preferred embodiment, the
outlet face is rendered black by inclusion of black within or
between cladding layers. The method includes stacking a plurality
of clear strips of plastic, placing a double sided, dark colored
adhesive between each strip of plastic, pressing the stack,
forming, at two opposite ends of the stack, a back face and an
outlet face, and connecting at least one reflector to the back
face.
Inventors: |
Veligdan; James T. (Manorville,
NY) |
Assignee: |
Scram Technologies, Inc.
(Dunkirk, MD)
|
Family
ID: |
24965077 |
Appl.
No.: |
10/389,398 |
Filed: |
March 14, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
737732 |
Dec 15, 2000 |
6535674 |
Mar 18, 2003 |
|
|
Current U.S.
Class: |
385/120;
348/E5.143; 348/E9.05 |
Current CPC
Class: |
G02B
6/08 (20130101); H04N 9/3141 (20130101); H04N
9/72 (20130101) |
Current International
Class: |
G02B
6/06 (20060101); G02B 6/08 (20060101); H04N
9/72 (20060101); H04N 5/74 (20060101); G02B
006/04 () |
Field of
Search: |
;385/120,134,135,136,137,141 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Veligdan, "Unique Interactive Projection Display Screen", Sep. 29,
1997, 7 pages. .
Beiser, et al., "Ten Inch Planar Optic Display", Proceedings of the
International Society for Optical Engineering (SPIE), vol. 2734,
Apr. 1996, 9 pages. .
Yoder, "The State-of-the-Art in Projection Display: An Introduction
of the Digital Light Processing DLP", Texas Instruments Web Site,
Mar. 1997, 5 pages. .
DeSanto, et al., "Polyplanar Optical Display Electronics",
Proceedings of the International Society (SPIE), vol. 3057, Apr.
1997, 12 pages..
|
Primary Examiner: Nasri; Javaid H.
Attorney, Agent or Firm: Reed Smith LLP McNichol, Jr.;
William J. Esserman; Matthew J.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The application is a divisional of U.S. patent application Ser. No.
09/737,732, filed Dec. 12, 2000, issuing on Mar. 18, 2003 as U.S.
pat. No. 6,535,674.
Claims
What is claimed is:
1. A method of producing a stacked optical waveguide panel,
comprising: coating a plurality of sheets on each of two faces with
a first substance having an index of refraction lower than that of
the sheets; placing a first coated sheet into a trough sized larger
than the first coated sheet; filling the trough with a thermally
curable epoxy; stacking the plurality of coated sheets within the
filled trough; curing the epoxy; forming, at two opposite ends of
the stack, a back face and an outlet face; and providing at least
one reflector substantially at the back face.
2. The method of claim 1, wherein said stacking is repeated until
between approximately 500 and approximately 800 sheets are
stacked.
3. The method of claim 1, further comprising applying substantially
uniform pressure to the stack to produce a substantially uniform
level of epoxy between adjoining coated sheets.
4. The method of claim 1, wherein said curing comprises baking at
80 degrees Celsius.
5. The method of claim 1, wherein said providing comprises
connecting the at least one reflector within the stack.
6. The method of claim 1, wherein said providing comprises
connecting the at least one reflector outside the stack.
7. The method of claim 1, wherein the sheets are comprised of
glass.
8. The method of claim 1, wherein the sheets are comprised of
plastic.
9. The method of claim 1, wherein the epoxy is black.
10. The method of claim 9, wherein the first substance is
clear.
11. The method of claim 1, wherein the first substance is
black.
12. The method of claim 1, wherein said providing comprises
embossing the at least one reflector onto the back face.
13. The method of claim 1, wherein said forming comprises sawing
the stack to thereby form the back face or outlet face.
14. The method of claim 13, further comprising polishing the sawed
stack with a diamond polisher.
15. The method of claim 1, wherein the back face is planar.
16. The method of claim 1, wherein the back face is curved.
17. The method of claim 1, wherein the outlet face is planar.
18. The method of claim 1, wherein the outlet face is curved.
19. The method of claim 1, further comprising providing a diffusive
material between the at least one reflector and the back face.
20. The method of claim 1, wherein the at least one reflector
comprises a diffusive element therewithin.
21. The method of claim 1, wherein said providing comprises
applying the at least one reflector to the back face as a
coating.
22. The method of claim 1, wherein said providing comprises gluing
the at least one reflector to the back face.
23. The method of claim 1, wherein said providing comprises
applying the at least one reflector to the back face as a
reflective tape.
24. The method of claim 1, wherein said providing comprises
connecting the at least one reflector to a surface of the back
face.
25. A method of forming an optical waveguide panel, comprising:
stacking a plurality of clear strips; placing an adhesive between
each strip; pressing the stack; forming, at two opposite ends of
the stack, a back face and an outlet face; and providing at least
one reflector substantially at the back face.
26. The method of claim 25, wherein said providing comprises
embossing the at least one reflector onto the back face.
27. The method of claim 25, wherein the strips are about 3/4" by
40", and approximately 20/1000" thick, in dimension.
28. The method of claim 25, wherein the stack includes about 2000
to about 3000 of the strips.
29. The method of claim 25, wherein the strips are glass.
30. The method of claim 25, wherein the strips are plastic.
31. The method of claim 25, wherein the strips are approximately
0.010"-0.020" thick.
32. The method of claim 25, wherein the adhesive is between 1/1000"
to 2/1000" thick.
33. The method of claim 25, wherein the adhesive comprises a
material having a lower index of refraction than that of the clear
strips.
34. The method of claim 25, wherein the adhesive is double sided
tape.
35. The method of claim 25, wherein the adhesive is black.
36. The method of claim 35, further comprising coating the clear
strips on each of two faces with a cladding material, wherein the
cladding material is clear.
37. The method of claim 25, further comprising coating the clear
strips on each of two faces with a cladding material, wherein the
cladding material is black.
38. The method of claim 25, wherein said providing comprises
embossing the at least one reflector onto the back face.
39. The method of claim 25, wherein the back face is planar.
40. The method of claim 25, wherein the back face is curved.
41. The method of claim 25, wherein the outlet face is planar.
42. The method of claim 25, wherein the outlet face is curved.
43. The method of claim 25, further comprising providing a
diffusive material between the at least one reflector and the back
face.
44. The method of claim 25, wherein the at least one reflector
comprises a diffusive element therewithin.
45. The method of claim 25, wherein said providing comprises
applying the at least one reflector to the back face as a
coating.
46. The method of claim 25, wherein said providing comprises gluing
the at least one reflector to the back face.
47. The method of claim 25, wherein said providing comprises
connecting the at least one reflector to a surface of the back
face.
48. The method of claim 25, wherein the adhesive is about 1/1000"
to 2/1000" thick.
49. The method of claim 25, wherein said pressing comprises
pressing the stack with a pressure of at least 1,000 pounds.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed generally to a planar optical
display, and, more particularly, to a high contrast front
projection display panel and a method of making a high contrast
front projection display panel.
2. Description of the Background
Video display screens typically use cathode ray tubes (CRTs) for
projecting an image onto the outlet face of the screen. A typical
screen of this type has a width to height ratio of 4:3 with 525
vertical lines of resolution. An electron beam must be scanned both
horizontally and vertically on the screen to form a number of
pixels, which collectively form the image. Conventional cathode ray
tubes have a practical limit in size and are relatively deep to
accommodate the required electron gun. Larger screen televisions
are available which typically include various forms of image
projection for increasing the screen image size. However, such
screens may experience limited viewing angle, limited resolution,
decreased brightness, and decreased contrast, particularly in
display screens using front projections. This is, in part, due to
the use of white screens to allow the screen to reflect the front
projection back to the user. Thus, because the screen is white, the
darkest black level that can be displayed is "screen white", the
color of the screen when the projection is off, due to the fact
that black light cannot be projected. Consequently, the projection
must be either on, or off, to produce white, or black,
respectively. Thus, where black is viewed on a front screen
projection system, the viewer is actually seeing the white of the
background, i.e the absence of projected light, which the human eye
sees as black in the context of the white light projected elsewhere
on the background, meaning that the presence of the optical
spectrum projected onto the white background forms a "whiter than
white" color, which the eye sees as white. This is the reason that
a room must be darkened in order for a viewer to see black on a
front projection screen.
Optical panels can be created using a plurality of stacked
waveguides, and may be rendered black using at least one black
cladding layer between transparent cores of the waveguides. The
cladding layers disclosed therein have a lower index of refraction
than the waveguide cores for effectuating substantial internal
reflection of the image light channeled through the cores, and
thereby improve contrast, i.e. thereby improve the appearance of
black images on a screen. Such optical panel displays have
typically been operated in a rear projection mode.
Therefore, the need exists for a display panel that allows for
front projection, while also providing the appearance of a black
screen to improve viewing contrast and to eliminate the need to dim
lights in order to allow a viewer to see black images.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to an optical display panel which
provides improved viewing contrast for front projection
applications. The optical panel includes a plurality of stacked
optical waveguides, wherein each waveguide has a back face and an
outlet face at opposing ends of each waveguide, and wherein each
waveguide is formed of a core between an opposing pair of cladding
layers, and at least one reflector connected to the back face of at
least one waveguide, wherein the at least one reflector receives
image light incident through at least one waveguide from the outlet
face, and wherein the at least one reflector redirects the image
light back through the at least one waveguide out of the outlet
face. In the preferred embodiment, the outlet face is rendered
black by inclusion of black within or between cladding layers.
The present invention is also directed to a method of producing a
stacked optical waveguide panel for front projection applications.
In one preferred embodiment of the present invention, clear strips
of plastic, which are preferably approximately 3/4" by 40", and
approximately 20/1000" thick, are stacked, with a thin double sided
black adhesive strip between each plastic strip. The stack may
include 2000-3000 of the strips. The strip stack is then pressed
under high pressure to eliminate air bubbles and improve adhesion.
Another method includes coating a plurality of glass sheets on each
of two faces with a first substance having an index of refraction
lower than that of the glass sheets, placing a first coated glass
sheet into a trough sized slightly larger than the first coated
glass sheet, filling the trough with a thermally curing black
epoxy, stacking the plurality of coated glass sheets within the
filled trough, curing the epoxy, forming, at two opposite ends of
the stack, a back face and an outlet face, and connecting at least
one reflector to the back face.
The optical display panel for front projection applications solves
problems experienced in the prior art by providing a display panel
that allows for front projection, while also providing the
appearance of a black screen to improve viewing contrast and to
eliminate the need to dim lights in order to allow a viewer to see
black images.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
For the present invention to be clearly understood and readily
practiced, the present invention will be described in conjunction
with the following figures, wherein:
FIG. 1 is an isometric view illustrating a cross section of a high
contrast front projection display panel;
FIG. 2 illustrates the use of a high contrast front projection
display panel for movie projection;
FIG. 3A is a cross sectional view of a high contrast front
projection display panel having a planar diffusor and planar
reflective portion;
FIG. 3B is a cross sectional view of a high contrast front
projection display panel having a planar diffusor and an angled
reflective portion;
FIG. 3C illustrates the reflection of light in a high contrast
front projection display panel;
FIG. 3D is a cross sectional view of a high contrast front
projection display panel having a diffusive reflector;
FIG. 3E is a cross sectional view of a high contrast front
projection display panel having an embossed diffusive reflector;
and
FIG. 4 is an isometric view illustrating a plurality of stacked
waveguides.
FIG. 5 is an enlarged illustration of the selected area in FIG. 3C.
FIG. 5 illustrates, in detail, the reflection of light in a high
contrast front projection display panel.
DETAILED DESCRIPTION OF THE INVENTION
It is to be understood that the figures and descriptions of the
present invention have been simplified to illustrate elements that
are relevant for a clear understanding of the present invention,
while eliminating, for purposes of clarity, many other elements
found in a typical optical display panel. Those of ordinary skill
in the art will recognize that other elements are desirable and/or
required in order to implement the present invention. However,
because such elements are well known in the art, and because they
do not facilitate a better understanding of the present invention,
a discussion of such elements is not provided herein.
FIG. 1 is an isometric view schematic illustrating a display panel
10. The display panel 10 may include a plurality of stacked optical
waveguides 16a, an outlet face 16 at one end of a body 18 formed by
the plurality of stacked waveguides 16a, a back face 12 at a second
end of the body 18, at least one reflector 19 that reflects light
within the body 18 at the back face 12, and a light generator
21.
The body 18 is preferably solid and receives light 14 along the
surface of the outlet face 16. The light 14 is passed through the
body 18 after entering the outlet face 16, and is reflected back
through the body 18 from the at least one reflector 19 to the
outlet face 16. In a preferred embodiment of the present invention,
the body 18 is formed of the length, height, and width of the
plurality of stacked waveguides 16a.
The plurality of stacked waveguides 16a forms the body 18 of the
panel 10, forms at one end of the stack 16a the back face 12, and
at a second end the outlet face 16. The waveguides 16a may be
formed of any material known in the art to be suitable for passing
electromagnetic waves therethrough, such as, but not limited to,
plastics, or glass. The preferred embodiment of the present
invention is implemented using individual glass or plastic or
polymer sheets, which are typically approximately 0.010-0.020"
thick, and which may be of a manageable length and width. The
polymer used may be a suitable plastic laminate, such as
Lexan.RTM., which is commercially available from the General
Electric Company.RTM., or any polymers or acrylics, such as
Plexiglass.
The waveguides 16a are in the form of sheets or ribbons extending
the full width of the outlet face 16 and are stacked to
collectively form at their upper ends the height of the outlet face
16. The waveguides 16a are disposed along their longitudinal light
transmitting axes. The number of waveguides 16a may be selected for
providing a corresponding vertical resolution of the outlet face
16. For example, 525 of the waveguides 16a may be stacked to
produce 525 lines of vertical resolution in the outlet face 16.
Since the waveguides 16a extend the full width of the outlet face
16, horizontal resolution may be controlled by horizontal
modulation of the image light 14.
Each of the plurality of waveguides includes a central core 26 for
channeling the image light 14 through the waveguides, and each core
26 is disposed between cladding layers 28. In a preferred
embodiment of the present invention, the cladding layers 28 extend
completely from the back face 12 to the outlet face 16 along the
entire width of the outlet face 16. A black layer 30 may be
disposed within or between adjoining cladding layers 28 for
absorbing ambient light 32 at the outlet face 16, and may form
multi-layer cladding layers 28. The term black is used herein to
encompass not only pure black color, but additionally, any
functionally comparable dark color suitable for use in the present
invention, such as dark blue. The black layer 30 is only necessary
within the viewable region of the outlet face, but, in a preferred
embodiment of the present invention, the black layer 30 extends
completely from the back face 12 to the outlet face 16 along the
entire width of the outlet face 16. Additionally, the cladding
layers 28 may be formed of gradients.
Each central core 26 has a first index of refraction. The cladding
layers 28 have a second index of refraction, lower than that of the
central core 26, for ensuring total internal reflection of the
image light 14 as it travels from the outlet face 16 to the back
face 12, and back to the outlet face 16. The core is thus
bi-directional. In a preferred embodiment of the present invention,
the cladding layers 28 are transparent in order to effectuate total
internal reflection of the image light 14, and thereby maximize the
brightness of the light 14 at the outlet face 16. The black layers
30, if separate from the cladding layers, may have any index of
refraction.
The back face 12 and outlet face 16 are formed by the plurality of
waveguides 16a , wherein one end of each waveguide 16a forms a back
face for that waveguide, and wherein the opposite end of each
waveguide 16a forms an outlet for that waveguide 16a . Each
waveguide 16a extends horizontally, and the plurality of stacked
waveguides 16a extends vertically. The light 14 may be displayed on
the outlet face in a form such as, but not limited to, a video
image 14a. Consequently, in a preferred embodiment the plurality of
waveguides 16a are stacked approximately parallel to the
horizontal, thus placing the outlet face 16 and the back face 12 in
the same plane from the horizontal and approximately equidistant
from the horizontal.
The outlet face 16 is formed by the plurality of stacked optical
waveguides 16a . The outlet face 16 is at one end of the body 18,
and receives light 14 from the light generator 21. In the preferred
embodiment, this light 14 is incident to the outlet face 16 at the
critical angle or lower of the waveguide 16a , thus allowing for
total internal reflection of the light within the waveguide 16a ,
thereby allowing for approximately all light projected from the
light generator 21 to reach the back face 12. The outlet face 16 is
defined as the front of the body 18. Additionally, the panel 10 has
a height from the top to the bottom of the outlet face 16, and a
width from the left to the right of the outlet face 16. The width
and height may be selected to produce width to height aspect ratios
of 4:3 or 16:9, for example, for use in a typical television
application.
The light generator 21 generates light 14 and passes the light to
outlet face 16. The light generator 21 may be a white light
projector, such as an overhead projector, or may include a light
source, and/or a light modulator, and/or imaging optics, such as a
video or movie projector. The light 14 may be initially generated,
for example, by the light source. The light source may be, for
example, a bright incandescent bulb, a laser, an arc lamp, an LED,
an RF excited gas discharge lamp, any solid state light source, or
any phosphorescent, luminescent, or incandescent light source. The
light 14 from the source may then be modulated by the modulator for
defining individual picture elements, known in the art as pixels.
Alternatively, the light may define a simple lighted item, such as
an on/off switch. The imaging optics may include light folding
mirrors or lenses. The imaging optics may be optically aligned
between the outlet face 16 and the light modulator for compressing
or expanding and focusing the light 14 as required to fit the
outlet face 16. The light 14, after entry into the outlet face 16,
travels through the panel body 18 to the back face 12, and reaches
the at least one reflector 19. The light 14 is projected at the
waveguide critical angle or lower over the outlet face 16, and is
thus directed generally horizontally upon reflection from the at
least one reflector 19 for projection outwardly from the outlet
face 16.
The at least one reflector 19 is connected to at least one of the
back faces 12, or is embossed into at least one of the back faces
12, in order to redirect the light 14, which is incident in a
direction generally horizontally inward through the body 18 from
the outlet face 16, back to a direction generally horizontally
outward from the outlet face 16. The at least one reflector may be
within, pressed into, or without, the body 18 at the back face 12.
The at least one reflector may be connected to the back face 12 by
an optical connection (via, for example, element 190 in FIG. 2),
being placed directly adjacent to the back face, or being glued to
the back face (again, see element 190 for example), with or without
air gaps, for example. The reflective portion of the reflector 19
may be, but is not limited to, a mirrored surface, such as a
retro-reflector, a total internal reflection (TIR) retro-reflector,
a reflective serration, a reflective coating, such as a reflective
tape, a lens or series of lenses, a micro-lens or series of
micro-lenses, a plane mirror, or a prism. Only light entering each
waveguide 16a at the critical angle or lower reaches the back face
reflector 19, as most ambient and other light will enter the
waveguide 16a at an angle greater than the critical angle, and will
consequently be absorbed by the cladding between the waveguides 16a
, rather than being reflected from the outlet face 16 to the back
face 19. Therefore, ambient and other light not entering the
waveguide at the critical angle or lower will not be reflected by
the at least one reflector 19 back to the outlet face 16, and light
entering at the critical angle or lower will be so reflected. The
at least one reflector may be a reflector 19 placed at the back
face 12 of each waveguide 16a , when covered with the at least one
reflector 19, causes reflection to occur back through the waveguide
16a and out the outlet face 16, or the at least one reflector 19
may cover several or all waveguide back faces 12 which constitute
the body
Additionally, in a preferred embodiment, the at least one reflector
includes a diffuser or disperser to reflect incoming light out of
the outlet face 16 at, for example, plus or minus 15 degrees from a
horizontal axis of the outlet face 16 (shown in FIG. 2 as angle
.alpha.) and plus or minus 60 degrees from a vertical axis of the
outlet face 16 (shown in FIG. 2 as angle .beta.). This dispersion
allows for viewing by a much larger number of viewers, as those
viewers can be off angle and, through the dispersion of the image
light, still view the image. For example, as shown in FIG. 2, a
movie projector may project a movie onto the outlet face 16, which
movie is then reflected back out the outlet face 16, at a dispersed
angle, to a wide viewing audience.
The diffuser 19a may be attached to the reflective portion 19b of
the reflector 19, between the reflective portion 19b and the at
least one back face 12, as shown in FIG. 3A. The diffuser 19a may
be planar in nature, as may be the reflective portion 19b, as shown
in FIG. 3A, or the reflective portion 19b may be angled, and may be
a retro-reflector, such as a TIR or mirrored surface, with a planar
diffuser 19a between that angled reflective portion 19b and the at
least one back end, as shown in FIG. 3B. In the embodiments of
FIGS. 3A and 3B, horizontal spreading is preferably completely
dependent on the diffuser 19a , while vertical spreading is
dependent on the diffuser 19a and the waveguide absorption angle,
as shown in FIG. 3C. The vertical and horizontal dispersion angles
should thus be tailored to the audience location, and the diffuser
angle of diffusion should be chosen accordingly.
In an additional preferred embodiment shown in FIG. 3D, the
reflector 19 is a diffusive mirror, which combines the reflective
portion 19b and the diffusor 19a into a single element. The
diffusive mirror may be a glass mirror or a plastic mirror, and
includes the reflective portion 19b on the diffusive mirror at a
plane farthest from the at least one back face 12. A diffusive
microstructure is preferably present on the glass or plastic under
the reflective portion 19a of the reflector 19. FIG. 3E illustrates
the reflector 19 as an embossed reflective and/or diffusive
microstructure, which is embossed directly onto the at least one
back face 12.
The plurality of stacked waveguides 16a, including the at least one
reflector, may be formed by several methods. The plurality of
stacked waveguides is shown in FIG. 4. A plurality of glass sheets
may be used as the central cores 26, and may be individually coated
with, or dipped within, a clear, or black, substance having an
index of refraction lower than that of the glass, such as, but not
limited to, polyurethane, clear coat containing dyes, silicones,
cyanoacreylates, low index refraction epoxys, plastics, and
polymers, thereby forming a coated glass sheet. This clear or black
substance is the opposed cladding layers 28. Where a clear cladding
layer is placed, a first coated glass sheet may then be placed in a
trough sized slightly larger than the first coated glass sheet. The
trough may then be filled with a thermally curing black epoxy. The
black epoxy need not possess the properties of a suitable cladding
layer.
After filling of the trough with either clear coated sheets in a
black epoxy, or black coated sheets in any epoxy, the coated glass
sheets are repeatedly stacked, and a layer of epoxy forms between
each coated glass sheet. The stacking is preferably repeated until
between approximately 500 and 800 sheets have been stacked. Uniform
pressure may then be applied to the stack, thereby causing the
epoxy to flow to a generally uniform level between coated glass
sheets. The stack may then be baked to cure at 80 degrees Celsius
for such time as is necessary to cure the epoxy, and the stack is
then allowed to cool slowly in order to prevent cracking of the
glass.
The back face 12 and the outlet face 16 may be cut as planar or
curved as desired, and the back face 12 may be specially shaped to
form a desired shaped surface to allow for proper operation of the
at least one reflector 19. The cut portions of the panel 10 may
then be polished with a diamond polisher to remove any saw marks.
The at least one reflector 19 is then added to the back face,
either in the form of a coating placed on the back face or faces
12, a mirror, lens, or prism glued to the back face or faces 12, or
a reflective attachment, such as a reflective tape, being fastened
to the back face or faces 12.
In an additional preferred embodiment, clear strips of plastic,
which are preferably approximately 3/4" by 40", and approximately
20/1000" thick, are stacked, with a thin double sided black
adhesive strip between each plastic strip. The stack may include
2000-3000 of the strips. The strip stack is then pressed under high
pressure to remove air bubbles and increase adhesion. In one
embodiment, the adhesive is Research AR8350, 1/1000" to 2/1000"
thick black double sided adhesive. The adhesive may be shades other
than black, such as dark blue, and preferably rolls out like a form
of tape, in a plastic/adhesive/plastic/adhesive format. The
pressure applied to the completed stack is preferably in excess of
1,000 pounds.
In a second embodiment of the present invention, the coated glass
sheets or plastic strips may be coated with a black substance, such
as spray paint, before being stacked with an adhesive, which need
not be a dark shade in this embodiment, between the strips, or
before being placed into the epoxy trough. In another embodiment of
the present invention, the coated blackened glass sheets may be
individually fastened using glue or epoxy. In another embodiment of
the present invention, both the clear substance and the black layer
could be formed of a suitable substance and placed, in turn, on the
glass core using sputtering techniques known in the art, or
deposition techniques known in the art.
Those of ordinary skill in the art will recognize that many
modifications and variations of the present invention may be
implemented. The foregoing description and the following claims are
intended to cover all such modifications and variations.
* * * * *